Zverev, the first hurdle was passed in Roland-Garros

It does not seem possible that a man – a world No.3 at that – who stands 1.98m (or 6ft 6ins if you prefer) could take baby steps. But that is exactly what Alexander (aka Sascha) Zverev has been doing on the Grand Slam circuit for the past couple of years.

He took so many of them at Roland-Garros that he eventually ran out of steam, losing to Dominic Thiem in the quarterfinals and winning only seven games as he did so. The spirit was willing but the body (or the hamstring, to be precise) was weak and in pain from the fourth game, he could not muster a decent challenge to the Austrian.

To get to the quarters, Sascha had played three consecutive five-set epics – that is more than enough steps, baby or otherwise, for any bloke. But at least he had reached his first major quarterfinal. He had reached his first Grand Slam milestone. And he had proved that he had the mental and the physical stamina to go the distance over five sets. It was all good.

"I showed that I'm physically one of the strongest players"

“I won three five-set matches in a row, got to my first quarterfinal,” he said. “[I showed] that I'm physically one of the strongest players, I think. I can last very long. There is a lot of talk of me not being able to play five sets, not being able to play long matches. I think I have showed that I can this week.”

From the moment Sascha packed his bags and joined the tennis merry-go-round, the big question has not been ‘if’ he could win a major championship but ‘when’.

The man has star quality: good looks, a big game, huge potential and brains. And waiting for all the component parts to come together at a Grand Slam has not been easy. Sascha may be bright but he is also 21 years old and 21-year-olds can get impatient.

When he lost to Hyeon Chung, his fellow NextGen star, in the third round of the Australian Open at the start of the year, he was crushed. Another opportunity had passed him by and still he had not proved himself on the big stage.

Federer: "I remember I had a hurdle to pass the quarters"

Roger Federer, a wise old head in the locker room, put a fatherly arm around him and offered some advice.

“I know people talk, but for the player, it's not easy if you've never been there,” Federer said. “I remember I had a hurdle to pass the quarters. I only did that back in 2003 for the first time. I was 22. Either I played quarters or I lost first round.

Now, when Federer was a young man, he was a racket smasher. He could get angry – very angry – and it cost him matches. So he decided to calm down. And then he became too calm, calm to the point that he did not care if he won or lost. It took time to find the right balance of competitive fire and ice-cold determination under pressure.

"Of course I am German, but still I have something Russian in me, and the best Russian players have always been a bit crazy"

It is the same for Sascha. He is German but his parents are from Russia and that streak of Russian passion is, he believes, one of his greatest weapons. It is also the reason why he split from his former coach Juan Carlos Ferrero earlier this year.

"Juan Carlos wanted to make me a very calm, balanced guy - who I never was and will never be,” Sascha told Frankfurter Allgemeine Zeitung. “Of course I am German, but still I have something Russian in me, and the best Russian players have always been a bit crazy. It has always helped me to be very active and aggressive."

Learning big match by big match when to bite his lip and when to let off some steam, Sascha is maturing quickly.

As the youngest of a tennis-playing family (his dad, Alexander Senior was a player and is now his coach, his mum Irina is also coach and his brother Mischa is the world No.64) he has never been allowed to get too big for his boots. And as a sensible lad, he simply does not believe his own publicity. He doesn’t even have a Twitter account.

An old head on young shoulders taking baby steps to greatness – it’s a cracking combination. And it is the future of men’s tennis.